KARL Stefanovic's ex-wife Cassandra Thorburn has opened up about the "dark days" she experienced following the split from her husband of 21 years.

In an interview with Woman's Day magazine, Thorburn, 46, says she has grieved the end of her relationship and that Stefanovic, 43, is now "dead" to her.

"I realised I was going through stages of grief, and to me it was like someone had died," she told the magazine.

"The children still have a father but I don't have a husband. He really is dead to me and no, we won't ever be friends again."

Adjusting to life as a single mother to the couple's three children Jackson, 18, Ava, 12 and River, 10, has been tough.

"There were days in the beginning I would get up, put on a brave face and drop the kids at school, then I'd get to the back door and I would lie in a heap for the rest of the day unable to move - there were very dark days," Thorburn said.

She knew for months before things officially ended that her relationship wasn't working anymore.

"I questioned and doubted myself about everything," she said.

"I slept on the couch in front of the fire for months because I didn't want to go near the marital bed. I was in a very dark place."

But now she says she's focusing on her children and being a good mother.

"I get up every day with only one purpose - to make sure my three beautiful kids are happy - everything else really doesn't matter," she said.

"I'm only concentrating on being strong in every way, and being the best mum I can be."

She made her first official media appearance earlier this month at The Australian Women's Weekly Women of the Future Awards.

Cassandra Thorburn at The Australian Women's Weekly on October 4th. Picture: Belinda Rolland

"I am looking towards my future as a single, confident, mother of three," she told Fairfax Media at the luncheon.

"It was a celebratory day for me. I am excited to start a new chapter."

Looking tanned and toned in a flirty pink Scanlan Theodore frock, Thorburn posed proudly for photographers as she arrived at the event. She kept her makeup natural and accessorised with tan heels, a gold clutch and simple silver jewellery.

"I was invited as me and I wasn't alone. I brought my girlfriend Cara along with me. It felt like a milestone," she told Fairfax Media of attending the event as herself - and not as Mrs Stefanovic.

Karl Stefanovic and his girlfriend Jasmine Yarbrough.

Over the weekend, Stefanovic gushed about his new girlfriend, shoe designer Jasmine Yarbrough, in his first interview since former Today co-host Lisa Wilkinson announced she was leaving the Nine Network.

He said Yarbrough, 33, who Woman's Day claims is yes to meet Stefanovic's children, has been his rock throughout a tumultuous year involving intense media scrutiny.

"She (Jasmine) has committed to my life ... my whole life, and her support is unwavering," he told The Sunday Telegraph.

"It would not be easy for Jasmine stepping into this. The focus sometimes is incredibly invasive. But she's strong, full of light, life and laughter.''

Stefanovic and Yarbrough began dating just months after his split from Thorburn.